Stud wrench

ABSTRACT

A wrench for gripping and turning threaded studs to cause their removal from other structure comprises a main body for engaging the stud and a tapered pin extending transversely through the main body and through a jaw maans within the body. With the pin in a fully inserted transverse position, the main body is threaded to the stud until it engages the lower end of the jaw means. A take-up nut having left handed threads is threaded into the upper end of the main body until it bears against the jaw means. The tapered pin and the internal jaw means are movable a small amount axially within the main body so that when the takeup nut is tightened the lower end of the jaw means will bear firmly against the end of the stud, thereby locking the main body to the stud and enabling the turning of the main body to unscrew the stud. Transverse movement of the pin in the main body serves to release the wrench from the stud.

United States Patent Kisle et al. 1 Nov. 6, 1973 STUD WRENCH [76]Inventors: Adolph J. Kisle, 27855 Via Ventana, [57] ABSTRACT 52: ???gggg g fi z g? kgt g% A wrench for gripping and turning threaded studs toMountain View Calif 94640 cause then removal from other structurecomprises a main body for engaging the stud and a tapered pin ex- [22]Filed: May 4, 1972 tending transversely through the main body andthrough a jaw maans within the body. With the pin in [21] Appl 250420 afully inserted transverse position, the main body is threaded to thestud until it engages the lower end of [52] US. Cl. til/53.2, 29/240 thejaw means. A take-up nut having left handed [51] Int. Cl B25b 13/50threads is threaded into the upper end of the main body [58] Field ofSearch 81/532; 29/240 until it bears against the jaw means. The taperedpin and the internal jaw means are movable a small amount [56]References Cited axially within the main body so that when the take-upUNlTED STATES PATENTS nut is tightened the lower end of the jaw meanswill 1 549 041 8/1925 Berg 81/532 bear firmly against the end Ofthe Studthereby locking 7/1931 Roche," 81/532 the main body to the stud andenabling the turning of 2 33 157 12/1943 Bayes I U 1 532 the main body120 unscrew the stud. Transverse move- 2,775,153 12/1956 Parhaniemi81153.2 ment of the p in the m y serves to release the PrimaryExaminer-James L. Jones, Jr. Att0rney-Roger W. Erickson wrench from thestud.

10 Claims, 7 Drawing Figures STUD WRENCH BACKGROUND OF THE INVENTIONThis invention relates to an improved wrench for removing threaded studsfrom structures. When such studsare usedfor holding members together invarious structures they are usually installed with considerable torqueso as to be tightly secured in place. Consequently, when it laterbecomes necessary to remove them for replacement or salvage, an equalamount or perhaps even more torque may be required to accomplished thejob. In order to apply adequate removal torque it isessential to gripthe stud firmly and preferably in a manner that does not damage the studthreads. One general object of the present invention is to provide awrench that will solve this problem.

Yetanother object of the present invention isto provide a studwrenchthat is compact, easy to use and economical to manufacture.

Another object of the present invention is to provide a stud wrench thatcan be easily attached to a stud, that can be tightened with a hightorsional force to grip the stud firmly without damaging its threads soas to enable it to be unscrewed from supporting structure.

Another object of the present invention is to provide a wrench that maybe quickly and easily released from the stud after the stud has beloosened.

Other objects, advantages and features of our invention will becomeapparent from the following detailed description of one preferredembodiment taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE INVENTION In broad terms our stud wrenchcomprises a main body having a bore at its lower end with internalthreads for engaging a stud to be removed. At its upper end is anotherbore with internal left-handed threads for a take-up nut. Situatedinternally between the upper and lower threaded bores is a smooth boresection for retaining a pair of jaw members. These jaw members havematching tapered recesses that are aligned with aligned transverseopenings in the opposite sides of the main body and located at the levelof the smooth section. A transverse tapered pin extends through thealigned openings in the sidewalls and the recesses of the jaw members.When the main body of thewrench is initially attached to the stud beingremoved the tapered pin is pushed transversely so that its larger endportion is between the jaw members and its narrower end extends from theside of the main body. When torque is applied to the takeupnut itengages the upper jaw member which bears against the pin and transmits adownward force against the lowerjaw member and also the end of the stud.A continued application of torque causes the main body threads to gripthose of the stud, so that eventually sufficient torque in the samedirection will cause the stud to unscrew from its supporting structure.When the stud has been loosened, the pin is moved by the application offorce to its small end to the position where its large end will notprotrude from the other side of the main body. This affords sufficientclearance to release the grip of the main body on the stud threads,thereby facilitating easyremoval of the wrench.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view in perspectiveshowing a stud wrench embodying the principles of the present inventionas it appears just before being attached to a stud to be removed;

FIG. 2 is a view in side elevation and partially in cross section of thestud wrench of FIG. 1 after it has been attached to the stud;

FIG. 3 is a view similarto FIG. v2 showing the wrench with its elementsin the stud gripping position;

FIG. 4 is a view in section taken along line 3-3 of FIG. 3;

FIG. 5 is a fragmentary view in section showing the pin after it hasbeen moved to its releasing position;

FIG. 6 is a lower end view of the lower jaw member of our wrench; and

FIG. '7 is a view in perspective of an adapter to enable use of thewrench on various sizes of studs.

Referring to the drawing, FIG. 1 shows a stud wrench 10 embodying theprinciples of thepresent invention as it appears just prior to beingapplied to a stud 12 which is threadedly secured in some other structure14. Usually, when it is necessary to remove such a stud it is becausethe stud has become broken and corroded or otherwise damaged. Also, itis usually tightly gripped by the surrounding structure so thatconsiderable torque is required to loosen and remove it. The wrench 10provides a means for firmly gripping the stud so that the necessarytorque can be readily applied. If the stud was previously broken it maybe desirable to file its exposed end 16 so thatit is essentially flat.

The stud wrench 10 comprises a main body member 18 which preferably hasthe external shape of a standard hex nut. Although it could becylindrical, this hex shape or some other suitable flat sideconfiguration is preferred in order for the body member to be readilygripped for turning by a conventional tool. The body 18 is fairly long,being around lrto 2 or more times its diameter, and at its lower end itis provided with an axial bore having internal threads 20 that areright-hand threads of standard design so as to engage the stud that isto be removed. These latter threads extend into the lower end of thebody portion for a distance that is somewhat less than one half of itstotal length and they terminate at the lower end of a cylindrical cavity22 which is smaller in diameter than the threads 20. Extendingdownwardly from the upper end of the body member 18 is another axialbore having a series of internal threads 24 that are left-handed. Thesethreads extend downwardly within the body member for a distance that isless than one half of its length and they terminate at the upper end ofthe cylindrical cavity 22. Engaged with the threads 24 is a take-up nut26 preferably having astandard hex head portion 28 that is smaller indiameter than the main body member. At its lower end this take-up nut,which is somewhat shorter in length than the upper axial bore, has aconvex tip 30 so that its downward thrust can apply a concentrated forcenear its center axis.

Now, within the cylindrical cavity 22 is a pair of upper and lowercylindrical jaw members 32 and 34 that serve to transmit axial forcefrom the take-up nut 26 to the end of the stud being removed. The outerdiameter of these jaw members is such that they provide anormal slidingfit with the wall ofthe'cylindrical cav ity. The inner end faces 36 and38 of thejaw members 32 and 34 are spaced apart to form a gap 40. Ineach of these end faces is a transverse: tapered recess 42 whose axis isperpendicular to the longitudinal axis of the jaw members. When the jawmembers are made, they are first formed or machined as a single unit.Then, a transverse bore hole having a small, constant taper (e.g., anouter surface having an angle of about three degrees with the pin axis)is made through this unit near its axial center. Now, the unit issevered to form the two jaw members by removing (as by sawing) atransverse slice of material in a plane that includes the centerline ofthe tapered bore hole. The thickness of this slice may be around percentof the mean diameter of the bore hole so that the recess of each jawmember is not a full one half of a tapered bore hole.

The upperjaw member 32 has an upwardly extending portion 46 of a reduceddiameter which is engaged by the convex tip 30 of the take-up screw 26.The lower jaw member 34 has a similar downwardly extending portion 48ofa slightly smaller diameter with a knurled annular surface 50 forengaging the exposed end of a stud being removed.

On opposite sides of the main body portion are a pair of alignedopenings 52 and 54 whose axis is coincident with the axis of the taperedrecesses 42 and therefore perpendicular to the longitudinal axis of themain body member. These openings are preferably formed with the samedegree of taper as the recesses in the jaw members. Extending within thealigned opening 52 and 54 and through the jaw recesses 42 is a taperedpin 56 also having the same degree of taper as the recesses and theopenings. This pin has a length which is substantially greater than thediameter of the main body member with an enlarged head portion 58 at itslarger end and an enlarged cap 60 secured to its smaller end, both headportion and cap being larger in diameter than the openings 52 and 54.Preferably, this pin is made of a ferrous material so that it can bemagnetized. The pin is also movable back and forth within the main bodyportion and when it is in the position with its head portion against theside of the main body portion the openings 52 and 54 are substantiallylarger than the pin portions which they surround, thereby forming aconsiderable clearance around these portions. Obviously, when the pin ismoved to its opposite extreme position with its cap 60 against the sideof the main body member, as shown in FIG. 5, even more clearance occursaround the pin at the openings 52 and 54.

The operation of our wrench 10 in removing studs that are held fast inother structures may be readily explained with reference to FIGS. 1 4.Before the wrench 10 is attached to a stud to be removed, the take-upnut 26 is threaded upwardly so that its lower end does not engage theupper jaw member 32. The tapered pin 56 is moved inwardly until its headportion 58 is fully against the side of the main body portion (FIG. 3).Preferably, the lower jaw member 34 is also made ofa ferrous material sothat it will remain in position against the pin 56 byits magnetic forceeven when the wrench is not in use. Now, the main body portion isthreaded onto the stud 12 being removed until the end of the studengages the knurled end 50 of the lower jaw member and pushes the pinupwardly against the openings 52 and 54. The take-up nut 26 is nowrotated counter-clockwise to move it downwardly within the main bodymember, thereby causing its convex end 30 to engage the upper portion 46of the jaw member 32. Continued torque applied to the take-up nut causesthis upper jaw member to bear against the pin and the pin in turn tobear against the lower jaw member. This forces the knurled end of thelower jaw member to bear against the end 16 of the stud 12. As moretorque is applied, the jaw members 32 and 34 grip the pin and are forcedinto the end of the stud causing the main body member to grip the studfirmly. Although there may be some slight axial movement of the stud asthe tightening force is applied, this can be accommodated by theclearance around the pin afforded by the enlarged holes in the bodymember. Such movement enables the internal threads 20 to also produce agripping action on the stud. When the take-up nut has been tightenedsufficiently to secure the wrench to the stud, additional torque can beapplied directly to the main body member in the same direction by a toolhaving a longer lever arm. Under such leverage no stud can remain in itsthreaded position but will ultimately break use.

After the stud has been loosened the wrench 10 may be quickly and easilyreleased from the stud by applying an axial force to the cap 60 of thepin 56. This will move the pin within the main body member and therecesses of the jaw members, thereby immediately creating an axialclearance that releases the force on the end of the studfNow, thetake-up nut can be reversed and screwed outwardly and the main body canbe unscrewed from the stud in the opposite direction. I

From the foregoing it should be apparent that the present inventionprovides a highly effective tool for removing old, corroded or damagedstuds from various structures. Not only is our wrench easy to apply to astud but its quick release feature eliminates any timeconsuming problemsof removing the wrench from the stud. Moreover, our wrench hasrelatively few parts and can be readily made in different sizes tohandle large or small studs.

To accommodate various sizes of studs with different threads anddiameters within a given range we may use an adapter 62, as shown inFIG. 7. This has a hexagonal shaped head 64 and a tubular barrel portionwith external threads 66 that will fit the lower internal threads 20 ofthe main body member. Internal threads 68 of any given type are providedwithin the barrel portion to accommodate a particular stud size.Obviously, various sized adapters that are relatively inexpensive can beused with a single wrench to accommodate an equal number of differentstuds.

To those skilled in the art to which this invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

We claim:

1. A wrench for removing threaded studs from supporting structurecomprising: i

a main body having a lower bore extending axially upwardly from itslower end with internal threads for engaging the stud to be removed;

an upper bore with left handed internalthreads extending axiallydownwardly from its upper end, and a passage interconnecting said upperand lower bores;

a take-up nut threadly engaged in said upper bore;

a pair of movable upper and lower jaw members within said passage havingopposed, spaced apart and transverse inner faces and tapered recessesexmain body has flat outside surfaces forming a hexagonal shape.

tending diametrically across said opposed, transverse inner faces;

a pair of openings in opposite sides of said body member having alignedaxes that extend through said passage, said axes being substantiallyperpen- 5 dicular to the central axis of said body member and parallelwith the axes of said jaw recesses;

and an axially movable tapered pin extending through said main bodyopenings and through said recesses so that said jaw members will gripsaid pin when said take-up nut is rotated to bear on said upper jawmember while said lower jaw member bears against the end of the stud tobe removed.

2. The wrench as described in claim 1 wherein said 3. The wrench asdescribed in claim 1 wherein said 4. The wrench as described in claim 1wherein said pin has a slightly conical outer wall that tapers atroughly an angle of 3 with respect to its central axis.

5. The wrench as described in claim 1 wherein said pin is magnetized tohave the opposite polarity'as said lower jaw member so as to hold it inplace when the wrench is not in use.

6. The wrench as as described in claim 1 wherein said passage is acylindrical smooth sided bore having a smaller diameter than said upperand lower threaded bores.

7. The wrench as described in claim 1 including an adapter means havinga tubular body and a head means at one end thereof, said tubular bodyhaving outer threads to match the threads of said lower bore and innerthreads adapted to fit smaller studs.

8. The wrench as described in claim 2 wherein said take-up nut has ahexagonal shape that is smaller than said main body.

9. The wrench as described in claim 1 wherein said take-up nut has aconvex lower end surface that bears against the upper end of said upperjaw member.

10. The wrench as described in claim 1 wherein said lower jaw member hasan annular knurled surface on its lower end adapted to engage the end ofa stud to be removed.

1. A wrench for removing threaded studs from supporting structurecomprising: a main body having a lower bore extending axially upwardlyfrom its lower end with internal threads for engaging the stud to beremoved; an upper bore with left handed internal threads extendingaxially downwardly from its upper end, and a passage interconnectingsaid upper and lower bores; a take-up nut threadly engaged in said upperbore; a pair of movable upper and lower jaw members within said passagehaving opposed, spaced apart and transverse inner faces and taperedrecesses extending diametrically across said opposed, transverse innerfaces; a pair of openings in opposite sides of said body member havingaligned axes that extend through said passage, said axes beingsubstantially perpendicular to the central axis of said body member andparallel with the axes of said jaw recesses; and an axially movabletapered pin extending through said main body openings and through saidrecesses so that said jaw members will grip said pin when said take-upnut is rotated to bear on said upper jaw member while said lower jawmember bears against the end of the stud to be removed.
 2. The wrench asdescribed in claim 1 wherein said main body has flat outside surfacesforming a hexagonal shape.
 3. The wrench as described in claim 1 whereinsaid openings in said main body have substantially the same degree oftaper as said pin.
 4. The wrench as described in claim 1 wherein saidpin has a slightly conical outEr wall that tapers at roughly an angle of3* with respect to its central axis.
 5. The wrench as described in claim1 wherein said pin is magnetized to have the opposite polarity as saidlower jaw member so as to hold it in place when the wrench is not inuse.
 6. The wrench as as described in claim 1 wherein said passage is acylindrical smooth sided bore having a smaller diameter than said upperand lower threaded bores.
 7. The wrench as described in claim 1including an adapter means having a tubular body and a head means at oneend thereof, said tubular body having outer threads to match the threadsof said lower bore and inner threads adapted to fit smaller studs. 8.The wrench as described in claim 2 wherein said take-up nut has ahexagonal shape that is smaller than said main body.
 9. The wrench asdescribed in claim 1 wherein said take-up nut has a convex lower endsurface that bears against the upper end of said upper jaw member. 10.The wrench as described in claim 1 wherein said lower jaw member has anannular knurled surface on its lower end adapted to engage the end of astud to be removed.